This landmark 10,500m² building, hidden behind a giant green wall of 350,000 plants, is the first new build scheme to achieve a Nabers UK 5.5-star ‘Design Reviewed’ target rating for landlord energy consumption. Its designers also set out to minimise upfront embodied carbon. The as-built figure of 620kg CO_2e.m^-2 is impressive given that, when it was designed in early 2020, there were ‘no targets and no definition for 90% of what we were talking about’, says Wyatt.

The building has been developed by ECF (formerly The English Cities Fund), a joint venture between developer Muse, Legal & General and Homes England. Its outstanding green credentials are the result of a committed developer and it being the first scheme to be built to Muse’s sustainable development brief, which Cundall helped draft.

‘We worked with Phil Marsden, from Muse, from RIBA Stage 0, to help set the brief for the entire design team at the beginning,’ says Wyatt. ‘We set clear objectives, aspiring to achieve the lowest carbon, the best health and wellbeing, and the best biodiversity increase we possibly could’.

The building’s holistic sustainability strategy means that it is Well Building Standard-enabled. Wyatt says this will ensure its tenants can achieve Well certification with their category B fit-out and its subsequent operation. ‘We went through a fit-out pre-assessment, so the landlord has already obtained 20-30% of the credits needed for any occupier coming to Eden who is looking to Well certify,’ he explains.

Wellbeing features incorporated into the landlord’s design encourage tenants to use the stairs, rather than take the lift, by incorporating daylight into the stair core and locating it so it’s easily accessible from reception.

Fresh air supply rates have also been increased on the office floors. The building’s location on a major road junction precluded the use of openable windows, so it has a full mechanical ventilation system. At the time of its design, most commercial offices had a fresh air rate of 12L.s^-1 per person, but, at Eden, this has been increased to 16L.s^-1 per person, which, Wyatt says, gives much better air quality.

A 4-pipe fan coil system is used to maintain comfort on the office floors, with heating and cooling provided by roof-mounted air source heat pumps. The fan coil units are supplied with fresh air ducted to the rear of the units from roof-mounted air handling units (AHUs).

The increase in fresh air supply rate enables an element of free cooling to be provided by the AHUs. ‘Too much air and you have an energy penalty, but a 16 L·s^-1 per person, the balance is about right; you get an energy increase for the fans, but you get an energy benefit from the free cooling,’ explains Wyatt.

Cooling loads have been kept low by the designers adopting a small power load of only 8W.m^-2. At the time, the British Council for Offices’ (BCO’s) recommended a small power load of 25W.m^-2, based on historic technologies, which, Wyatt says ‘would have caused everything to be oversized and to work inefficiently’.

The ‘punched’ windows allow the building to achieve good daylight levels on the office floors

To come up with the more appropriate small power load, Cundall worked with the project’s MEP concept engineers, Atelier Ten. ‘We convinced Muse to very bravely go for 8W.m^-2, which is enough to power a laptop and monitor,’ says Wyatt. Adopting this lower figure meant that, when the building was first marketed, it was not BCO-compliant. However, the BCO has subsequently updated its guidance to 6W.m^-2.

In addition to allowing for a reduced small power load, the design cooling loads are also kept to a minimum by the building’s envelope. This eschews curtain walling in favour of a solid façade with what Wyatt calls ‘punched’ windows, as opposed to using full-height glazing.‘We said we wanted to achieve an overall façade U-value of circa 0.6 to 0.65W.m^-2.K^-1, which is very challenging to achieve with curtain walling,’ says Wyatt. This has resulted in a façade where the solid areas have a U-value of just 0.15W.m^-2.K^-1, while the windows have a U value of 1.4W.m^-2.K^-1. Airtightness is 2m³.h^-1.m^-2 @ 50Pa.

What gives the building its unique appearance is that the solid elements of the façade are covered by a living wall of 350,000 plants. These form a surround to the windows and, because they are visible from inside the building, Wyatt says they contribute to biophilic health and wellbeing. Other benefits of the green wall include: contributing to the area’s biodiversity; absorbing pollution; reducing the urban heat island effect; and helping to lower the air temperature slightly around the heat pumps, which improves their performance.

In terms of cost, Wyatt says the façade was cheaper than a lot of other systems because, behind the greenery, it is ‘a very basic system’. There will be ongoing maintenance costs, however.

Daylight levels on the office floors are also based on Well criteria, rather than on daylight factor. The office floors are described by Wyatt as ‘reasonably narrow’, but through careful design, the punched window solution achieves good daylight levels.

Climate-based daylight modelling was used to optimise the location of the façade’s 40% glazed area. ‘We did a lot of solar modelling of the façade; we’ve distributed the glazing so there is slightly less on the south and slightly more on the north, to help create uniform daylight distribution,’ explains Wyatt.

Optimising the position and area of glazing, combined with additional shading from the green wall, helps keep solar gains to a minimum. To ensure the offices are comfortable, the fan coil units are controlled zonally, based on four zones per floor. At the time the scheme was designed, Wyatt says a lot of commercial offices were designed to maintain an internal temperature of 22°C, with very little leeway, which meant simultaneous heating and cooling could occur on the same floor plate. For Eden, the heating setpoint is 20°C, while the cooling is set at 25°C.

Wyatt is keen to explain that, even with a 5K dead band, there is no compromise on comfort because the scheme has been designed based on maintaining the operative temperature, which is a combination of air temperature and radiant temperature. He says spaces with full-height glazing often have a high radiant temperature, so a low air temperature is required to maintain a comfortable operative temperature.

The green wall of 350,000 plants incorporates automatic irrigation, fed using rainwater harvested from the building’s roof

At Eden, optimising the glazed area and incorporating a green wall has helped reduce radiant temperatures in the offices, enabling the air temperature to be elevated while still maintaining a comfortable operative temperature. ‘Even though we have a higher air temperature within the space, the operative temperature is the same or better than that of a fully glazed office building,’ Wyatt explains.

The higher air temperature in the offices is just one element of the building’s outstanding low-energy design that has helped it achieve a Nabers UK 5.5-star ‘Design Reviewed’ rating. Nabers is the energy efficiency rating system that is gaining traction because a commercial office’s predicted energy performance is subsequently verified once the building is operational, through annual energy consumption monitoring.

Wyatt says experience from Australia (where Nabers originated) shows that, when a building is first occupied, its Nabers rating is expected to drop by about one star. ‘The idea is that the rating improves over a couple of years as the building is fine-tuned,’ he adds. ’According to the Better Buildings Partnership, we can probably expect a half-star incremental increase each year; so, if we achieve 4.5 stars in the first year, we would expect 5 stars in the second, and 5.5 stars in the third, which would be a really positive story.’

Cundall is already working with some of the building’s future tenants to ensure they don’t compromise the Nabers rating. Alongside the tenants, Wyatt says one of the greatest challenges was ‘ensuring that requirements for operational energy, embodied carbon and biodiversity net gain were written into the building contract in a meaningful way, with a clear methodology for measuring, reporting and certifying performance in use’. This meant providing contractor Bowmer + Kirkland with evidence that the design would work. Bowmer + Kirkland will update the rating using as-built information now that it is complete.

Wyatt says a key lesson from this project is that bringing the Nabers independent design review forward from RIBA Stage 4 (technical design) to Stage 3, when designs usually go out to tender, would give contractors more confidence in the operational energy requirements, although this means doing the calculations and simulation much earlier.

Once fully occupied, Eden will be enabled to run solely on 100% renewable electricity, which will further enhance its already outstanding sustainability and wellbeing credentials. 

About the author
Simon Wyatt MCIBSE is a partner at Cundall and chair of the CIBSE Knowledge Generation Panel

The post Case study: Manchester’s garden of Eden appeared first on CIBSE Journal.

It won Project of the Year – Leisure at the 2024 CIBSE Building Performance Awards with judges impressed by its careful, low carbon design and application of technology.

What’s more, the performance data has been used as an exemplar case study by the UK Net Zero Carbon Buildings Standard, to help establish a best-practice benchmark for operational and embodied carbon for future leisure centre buildings.

To achieve this remarkable feat, building services engineers Max Fordham – working with architects FaulknerBrowns, the client and main contractor – have taken every design decision as an opportunity to minimise energy consumption further.

As such, the building incorporates a range of passive and active environmental technologies, including the extensive use of daylight and mixed-mode ventilation. In addition, heat is provided by air source heat pumps (ASHPs) incorporating load-shedding controls, while the complex is crowned by a giant biosolar roof that provides up to 20% of the building’s electricity needs.

The £57m sport centre’s low-energy design is a response to the university’s campus energy and sustainability masterplan. Developed by Max Fordham under a previous project, the masterplan includes a requirement for all new buildings to achieve Breeam Outstanding and a Display Energy Certificate (DEC) ‘A’ rating in operation.

Large rectangular rooflights supplement daylight in the pool area

To achieve DEC ‘A’, the design had to target a maximum EUI of 218kWh·m^-2 per year. Ambitiously, Max Fordham set out to meet this already challenging target without the use of fossil fuels. ‘When we started to develop the design in 2016, gas boilers were the standard solution, but we said “this building is not going to complete until 2022, when Grid carbon will be lower, so we should not be basing our design on fossil fuels”,’ says Mark Palmer, director and sports leader at Max Fordham. Opting for an all-electric solution would also ensure the building’s carbon emissions fall further as the Grid continues to decarbonise.

The university’s brief to the design team was for a sports centre with a 25m swimming pool, an eight-court sports hall, 175-station fitness suite, climbing wall, ski simulator, and fitness studios, along with offices and teaching spaces.

Palmer says the starting point in developing the building’s form was to separate the swimming pool from the ‘dry’ areas (the sports hall, fitness suite, and so on), so that the circulation space between can form an environmental buffer zone.

Unusually, the design places the sports hall on top of the ground-floor fitness suite and changing rooms. ‘One of the key decisions was to put the sports hall on the first floor, to ensure that it and the swimming pool could benefit from rooflights, to provide passive heating and daylight, which saves energy and is good for wellbeing,’ says Palmer.

One of the striking giant fans set into the ceiling in the gym. The fans have been designed to generate air movement to reduce the need to drive down the fitness suite air temperature

Flexibility is key to keeping the building’s footprint and embodied energy to a minimum. The swimming pool, for example, has a floating floor, to do away with the need for a learner pool; the squash courts are separated by a moveable partition to enable them to be converted into additional studio space; and the studio spaces incorporate a moveable partition that allow them to flex to accommodate a variety of class sizes and activities. The compact building’s high-performance envelope has been kept deliberately simple to avoid complex junctions and cold bridges.

In addition, the swimming pool envelope has been fortified with additional insulation, to deal with the higher air temperature and humidity in the space. Employing a simple, system-build envelope solution made it easier to build and, Palmer says, gave contractor Wates Construction ‘a fighting chance of delivering on the design airtightness and thermal performance in practice’.

The rooflights in the sports hall and swimming pool are designed to open. They are arranged in strips in the sports hall, strategically positioned between the badminton courts to allow daylight in while minimising the impact of glare on the players.

Max Fordham has eschewed natural ventilation for an innovative cooling and mechanical ventilation solution for the intensively used, 175-station fitness suite. Alongside a conventional fan coil cooling system, a series of large-diameter, high-volume, low-speed horizontal fans have been recessed into the ceiling, like the slowly spinning rotor blades on a series of upturned helicopters. These giant fans have been designed to generate air movement to reduce the need to drive down the fitness suite air temperature. The large fans are supplemented by 13 smaller fans concealed above the ceiling.

The conventional way to deliver comfort to a fitness suite is to lower the air temperature to help people lose heat. Sport England’s guidance, for example, suggests maintaining temperatures as low as 16°C-18°C. But Palmer says this can result in ‘very high energy use’ that often ‘fails to deliver occupant comfort’ because, when we are sedentary, radiation is the primary mechanism of heat exchange. As exercise intensity increases, however, convection and, eventually, the evaporation of sweat become the dominant modes of user heat loss. ‘If the air in a gym is cool, still and humid, your sweat is unable to evaporate to cool you down,’ Palmer explains.

For those undertaking high-intensity exercise, convective and evaporative transfer of body heat are increased significantly by air movement. ‘By creating air movement and controlling humidity, we are able to achieve much better levels of comfort at temperatures that are not as cold,’ Palmer adds. See ‘Fit for purpose’, CIBSE Journal October 2018 for more on this bit.ly/CJRav.

In addition to the giant fans, four-pipe fan coil units (FCUs) have been tucked out of sight above the suite’s slatted wood ceiling. The FCUs provide the space with heating and mechanical cooling. ‘The client was a bit nervous about the effectiveness of our giant fan solution, so the fan coil units have been sized to cool the space conventionally without the need to run the fans,’ says Palmer, who adds that the client need not have worried. ‘Everyone loves this solution: it’s striking to look at and it’s proven to be very effective.’

In addition to ensuring the university’s management and operations teams have a good understanding of the building and its systems, soft landings enabled the engineers to tweak the fan system once the fitness suite was fully operational. They estimate that increasing air movement in the fitness suite, as opposed to relying on a lower temperature setpoint, will result in a 10% reduction in energy use in peak summer conditions.

Heat for the building is supplied by five ASHPs via a low-temperature buffer vessel. To maximise ASHP efficiency, heating is at 45°C flow/40°C return, which, Palmer says, is ‘quite challenging when we need to heat the pool hall to 30°C. To operate the system at these low temperatures relies on high levels of heat recovery and a high-performance building envelope’. The solution also required non-standard fan coils, air handling unit coils and heat exchangers to exploit the low flow temperatures.

Reducing glare

Plots show the direct sun penetration at two points during the year. These simulations are conducted using a bespoke tool, Beam Tracer, created by Max Fordham to calculate specular reflections. Orange represents the direct sun transmitted through the glazing; pink is the reflection from the pool surface. As a result of the steep-angle reflections from direct sun through the top, lights remain at high level and do not enter the occupied zone, where they can cause glare. At low sun angles, some direct sun penetrates into the pool area and can cause glare to occupants. By carefully mapping the path of the sun, lifeguards can be positioned to avoid areas that experience glare from direct sun.

The ASHPs incorporate load-shedding controls to minimise peak heat loads and reduce their size, capital cost and embodied energy. Palmer says minimising heat loads, maximising heat recovery and using load shedding ‘has allowed us to squeeze the combined capacity of the heat pumps down to 525kW, around a quarter the capacity of boilers in a typical leisure centre’. This ensured the heat pump solution was space-efficient and economically viable.

The pool water heat exchanger, for example, has a heat demand of 500kW, which, under the usual control regime, would take up the full heat capacity of the ASHPs, leaving nothing for space and water heating. However, Palmer says the only time it needs to deliver this output is when it is heating the pool water up from cold.

For the majority of the time, the heat exchanger is only required to output about 50kW to maintain the water at a steady temperature – and because the pool water acts like a huge thermal battery, the system can wait until the demand for heat is lower. ‘We put a lot of work into ensuring the heat pumps are not oversized, because it would have been easy to think we needed four times as many heat pumps. But if you are in control of where the heat is going, it allows you to shed some of the loads,’ Palmer explains.

Two additional water source heat pumps are used to raise the water temperature from 45°C to 60°C to supply the hot water calorifiers.

In addition to the five heat pumps dedicated to heating, the sports centre has five, four-pipe heat pump chillers optimised to provide cooling, but which can also provide free heat to the building. These supply the FCUs with chilled water at 6°C/12°C. The units can simultaneously top up the thermal store using heat reclaimed from the cooling side. The heat generated by activity in the fitness suite and dance studios is captured and used to keep the pool warm and preheat hot water for the showers, explains Palmer. 

There is a heat recovery unit on the pool water filter backwash system, too. The backwash is used to clean the water filters. In addition, to maintain pool water quality, 30 litres of water is added to the pool per bather, with a corresponding amount removed. This water is used to flush the centre’s toilets.

Engineering the sports centre’s low-energy design was ‘the easy bit’, says Palmer, who adds that it is often the execution, rather than the design, that prevents schemes from achieving predicted energy performance. For Ravelin, Max Fordham was novated to Wates Construction under the two-stage design and build contract, and appointed by Wates Building Services to develop its installation and record drawings in Revit. The engineer also worked with Wates’ offsite manufacturer, Prism, to integrate prefabricated service modules and plant skids. ‘It meant we were able to take responsibility for the design from concept to installation,’ says Palmer.

Max Fordham also produced drawings for the client, with all CoBie asset information, as a full BIM project. Palmer is complimentary about how Wates Building Services (now SES) tackled the project. A two-stage procurement route ensured the contractor was able to price ‘every bit of kit specified, to avoid compromises with lower-efficiency alternatives’. Execution was also helped by the soft landings specification insisting that Wates appoint an independent commissioning manager (Banyards). Its task was no doubt helped by the building having more than 200 electricity and heat meters. ‘At completion, the building was properly and fully commissioned so that it performed well from the get-go,’ says Palmer.

Post-occupancy, the soft landings initiative requires Max Fordham to monitor the building and report each month on how the various spaces are performing – a task aided by the engineer having remote access to the BMS and meters.

There were also monthly meetings to gather client feedback. Palmer says: ‘If something was not working, it was raised at the meeting so that, by the next meeting, it had been resolved, which helped ensure the client never lost faith in the design and remained engaged in the low-energy strategy.’

A major challenge with sports buildings is the huge variation in occupancy throughout the day. In the evening, they are usually full and everything is running flat out, whereas, in the middle of the day, they are relatively empty. ‘M&E designs often only focus on meeting peak conditions and do not consider the other times when occupancy drops off,’ explains Palmer. ‘But you have some pretty powerful kit in this building, so you will waste a lot of energy if you don’t turn things down or off when occupancy drops.’

One issue raised post-occupancy was the level of local control that users should be given, particularly over the temperature of the fitness studios after complaints that these were either too hot or too cold.

Post-occupancy evaluation monitoring showed the rooms were performing as designed, with temperatures being maintained at 18°C, and CO₂ levels rising and falling, and the fresh air fans responding accordingly, depending on occupancy. After questioning users throughout the day, however, it became clear that when the spaces were used for high-intensity exercise classes, users found them to be too hot, whereas when they were used for a zen yoga class, for example, users were too cold. ‘We’ve now added a button to each studio to allow the temperature to be changed up or down a couple of degrees for an hour,’ says Palmer.

This approach has clearly worked, and highlights the benefits of a soft landings approach. Perhaps more impressive is that the scheme improved significantly on the original, challenging EUI target of 218kWh·m^-2 per year. 

The post Keeping fit with less energy: Ravelin Sports Centre appeared first on CIBSE Journal.

Thorough research and testing of the Diffusion Highline 235 modular fan coil range has resulted in a product that considers whole life costing through the use of TM65 and local sourcing to reduce transport miles, the judges added. Energy, acoustics, performance, and the flexibility modularisation brings to deployment and onsite repairs have also been considered.

Working closely with customers, Diffusion researched every UK fan coil on the market to assess how it could improve the design to meet the changing needs of the industry.

As a result, its Highline range has been increased to eight, the modularity of which now allows almost 300,000 configurations. This means customers can select a unit that exactly matches their performance requirements rather than having to over-specify, ensuring the lowest energy consumption.

At design stage, the emphasis was on using fewer materials, reducing the volume of materials transported, minimising carbon footprint, and lowering running costs per unit size.

Leveraging high-efficiency EC/DC motor and fan assemblies, the units achieve a specific fan power as low as 0.14W.L^-1.s^-1, significantly reducing energy consumption and operational costs. Forward-curved centrifugal fans provide the most efficient airflow and acoustic performance in all models. Further acoustic benefits are achieved through ‘0’ fire-rated foam insulation.

The unit’s heat exchangers are manufactured from solid drawn copper tubes, mechanically expanded into pre-formed collars in rippled plate aluminium fins. Multi-circuit design ensures maximum thermal performance. For optimum heat transfer into the airflow, electrical elements are 8mm-diameter, fully sheathed, stainless-steel rods, with spiral-wound fins.

Highline 235 is supplied with Diffusion’s Lifetime Eco wire-mesh filter, which can be simply vacuum cleaned in situ. It lasts the lifespan of the unit. 

ISO-grade media filters are also available. When filters need to be cleaned or replaced, they can be easily removed from either the side of the unit or from beneath it.

In spaces where noise levels significantly influence occupant satisfaction, the Highline 235 range can achieve noise levels ranging from NR25 to NR40. Discharge plenums are available in rectangular or circular spigots, and inlet and discharge attenuators are available in lengths to meet requirements.

British designed and manufactured with a short supply chain, 70% of Diffusion’s fan coil units (FCUs) are transported less than 24 miles to end users in London, keeping carbon emissions to a minimum. The modular, configurable design means building owners can reuse the FCUs by repositioning them.

The CIBSE TM65 data-collection methodology was used to collect accurate and detailed embodied carbon information about the system. Working from a component level, this methodology ensures data is comprehensive and up to date.

Diffusion uses its in-house test facility to offer volumetric, acoustic and thermal performance testing, and customers can watch their chosen products being tested and certified. They can also input their building’s design parameters into Diffusion’s software to select the ideal FCU for their required temperature and flowrate. This includes data on correct heat exchanger selection.

The judges said the range of innovations among award entries this year showed that innovation doesn’t need to be ‘epic’ to be influential and beneficial. They also illustrated the importance of product testing.  

• For more on the winners at the CIBSE Building Performance Awards, visit www.cibse.org/bpa

The post High fives for Highline 235: CIBSE award-winning fan coil unit appeared first on CIBSE Journal.

Retrofit has also become a companion to life sciences development, mainly because of a lack of new spaces that can handle the structural and services demands of life sciences buildings. There has also been a shift in demand for city-centre locations, driven by proximity to universities, hospitals and a skilled workforce.

Cambridge, Oxford and London, deemed as the life sciences’ ‘golden triangle’, are great examples of this. Both offices and retail have seen a decrease in demand, creating an opportunity to repurpose these spaces for science laboratories, where the demand remains strong. 

The retrofit challenge

All types of laboratories need supplementary ventilation and some form of fume extraction, and this can be a particular challenge for a retrofit in a built-up area.

The higher ventilation rates required to extract fumes from laboratories means risers need to be larger than those for offices to accommodate more intensive services, and ceiling void space needs to increase by 50cm to make room for larger duct work. Existing buildings that already have high floor-to-floor space, such as shopping centres, are more easily retrofitted as laboratories.

In the past, a lot of buildings were thought to be structurally unsuitable, as external vibrations hindered the ability for optical microscopes in labs to achieve stable images. However, recent technological advancements such as active vibration damping, which operates in a similar way to noise-cancelling headphones, have helped overcome such structural issues.

Specification of ventilation starts with a suitable selection of fume cupboards and biosafety cabinets, for the specific application and chemicals that are anticipated to be used. Ducted fume hoods are typically the most effective for removing fumes.

The placement of hoods must be carefully considered to capture contaminants effectively, by ensuring that there are no obstructions blocking airflow to the hood. Computational fluid dynamics (CFD) modelling is often needed to validate the design before implementation. 

A minimum air change rate must be achieved for safety purposes in laboratories and this is typically three times more than conventional office buildings, requiring larger HVAC facilities. 

It is important to consider where the fumes are discharged and their proximity to other air intakes and receptors.

Conventionally, air intakes must be separated from discharges by at least 10 metres, and fumes are discharged vertically at least three metres above other parts of the building. However, for city centres with an abundance of developments, more detailed assessments are often required.

When direct, ducted systems cannot be incorporated, recirculating systems with activated charcoal air filters and scrubbers can be considered, although these are expensive alternatives.

Higher ventilation rates and fume-extraction systems will have a significant impact on a building’s energy use, so it is essential that buildings services pay particular attention to energy efficiency.

As a first step, it is important to work with the scientists who will be occupying the buildings in the design stages, to optimise the parameters and the airflow design, and prevent overdesign. 

Where possible, spaces should be lab-enabled, rather than fully fitted-out. This will provide end users with an adaptable blank template they can fit-out however they want. This is more attractive than receiving a fully fitted-out space that may not meet specific requirements and could put occupiers off at due diligence stage, or lead to expensive refit financial and carbon costs.

Modulating the airflow to match actual demand reduces energy consumption during low-activity periods, while still providing adequate ventilation when needed.

Variable air volume flowrate systems and demand-control ventilation can adjust the ventilation rates based on real-time occupancy and contaminant levels. Implementing scheduling controls can also optimise ventilation operation based on occupancy patterns and laboratory usage schedules.

Rob van Zyl

Natural ventilation can be used in certain situations. There are other considerations such as prioritising recirculation over full ventilation by using activated charcoal filters or liquid scrubbing to wash the air as it passes through. Heat recovery systems must also be implemented wherever practical, to capture and reuse heat or coolness from exhaust air to precondition incoming fresh air.

Typically, the requirement for safe removal of fumes is to discharge fumes at least three metres above the highest point of buildings, and this means having tall and unsightly stacks.

In the UK, planning regulations impose restrictions on the height of stacks and exhaust vents as part of the overall planning permission process. This is primarily to address concerns of air pollution, visual impact, and potential adverse effects on the environment and neighbouring properties.

Planning authorities need evidence to show that vertical stacks are tall enough to adequately control the dispersion of pollutants and they will want to see how the visual impact of stacks on the surrounding landscape have been considered.

Stack heights need to be specified to minimise impact on air quality. They will be based on factors such as the type of emissions, local air quality standards, and the proximity of sensitive receptors, such as residential areas, schools, or hospitals.

The speed at which air is discharged from a ventilation system – the efflux velocity – can determine stack height. By increasing the velocity of vertical discharge, fumes can be pushed higher and the stack height reduced. CFD modelling can be used to predict whether or not the concentration of released fumes will exceed the required parameters of the nearby receptors. It should be borne in mind that higher efflux velocities require more energy. 

The importance of heat recovery

As there is a requirement for labs to have a lot of air circulating in the building, it is important to recover as much of its heat as possible. However, effectively capturing and using waste heat can be difficult in practice. In some cases, the temperature difference may be insufficient to extract heat efficiently, limiting the feasibility and effectiveness of heat recovery.

Integrating heat recovery systems can be difficult, as it will introduce pressure drops. It can also create foul air that can be corrosive, which means the ductwork must be made with corrosion-resistant materials that will not be damaged by this. 

Science buildings are one of the sectors being considered by the Net Zero Carbon Buildings Standard (NZCBS). Simon Wyatt, sustainability partner at Cundall, is leading the NZCBS¹ sector group and is collaborating with market leaders to create assessment frameworks for buildings in the sector. It is still early days for the sector, and there is a lot more data that is needed before benchmarking of life sciences buildings is taken seriously.

About the author:
Rob Van Zyl is a management board partner at Cundall

References:

1. UK Net Zero Carbon Buildings Standard www.nzcbuildings.co.uk

The post Science in the city: the challenge of retrofitting labs appeared first on CIBSE Journal.

It served as the city’s seat of governance for more than 600 years, but when York City Council relocated, it wanted to refurbish the historic complex and turn it into a digital hub for the 21st century.

Together, architect Burrell Foley Fischer and SGA Consulting set out to deliver the council’s vision.

The interior of the 15th- century York Guildhall

Alongside the creation of the digital hub, the project involved the refurbishment of the listed elements of the scheme to improve accessibility, occupant comfort and energy efficiency. It also included a new office extension and riverfront restaurant at the side of the complex.

The scheme’s numerous listed elements made for an extremely challenging refurbishment. Except for the listed cast iron radiators in the Victorian council chamber, all of the existing building services had to be replaced, as they were long past their prime. ‘We started by asking what interventions we could make to the listed buildings and then set about working out how to deliver these in the best possible way,’ says Bart Stevens, a director of SGA Consulting.

some materials were transported by river

The building’s location, adjacent to the River Ouse, made a river source heat pump (RSHP) the obvious solution to heat and cool the building. ‘The first time I went to the site, I took one look at the river and said “of course we’ve got to use this”,’ recalls Stevens.

Permission to use the river was obtained from the Environment Agency and the Canal & River Trust, and an unobtrusive route for the abstraction and discharge pipework was devised from the basement plantroom to the river.

Under the new scheme, 110kW of simultaneous heating and cooling is provided by a two-circuit, reverse-cycle RSHP. To optimise its efficiency, the heating circuit runs at 50^oC flow/45^oC return, while cooling is at 6^oC flow/12^oC return. The RSHP is also designed to recover heat if areas of the building require simultaneous heating and cooling.

Pipes taking water from the Ouse to the river source heat pump

A pragmatic fabric-first approach was adopted by SGA Consulting in developing the servicing strategy. Using the heat pump to service the new office extension and restaurant was relatively straightforward, because its fabric thermal performance exceeded Building Regulations minimum. However, the listed status of many existing elements and spaces meant opportunities to improve fabric thermal performance were limited. This had a major impact on how and where the heat pump-derived heat could be used.

The office extension and riverfront restaurant

The lower temperature of the heat pump heating circuit made it ideal as a heat source for underfloor heating, because the large floor area helps compensate for the lower temperature of the emitter. The heat pump is also used to supply heat to fan coil units (FCUs) in some of the office spaces. These incorporate oversized heating coils to compensate for the circuit’s lower flow temperatures.

Operating in reverse mode, the heat pump uses river water, extracted at up to 22^oC and returned at 25^oC, to also provide chilled water to the FCUs in south-facing river frontage rooms. ‘These rooms required cooling as well as heating, so we were justified in replacing the existing radiators with modern FCUs in these rooms,’ explains Stevens. 

Reinstating Victorian natural ventilation

SGA Consulting has resurrected the original Victorian ventilation system to help alleviate stuffiness and overheating in the Grade II*-listed council chamber.

The original building services proposal incorporated a series of FCUs to keep the council chamber comfortable. The units were to be placed outside the chamber and holes knocked through the wall to enable the units to circulate air. Historic England was not keen on the modifications, so an alternative solution had to be devised.

‘I said “I bet the Victorians had a way of ventilating the room”,’ recalls SGA Consulting’s Stevens. Low-level ventilation inlets had been identified in the external walls, hidden behind the cast iron radiators which also provide preheating to air entering the chamber. ‘After hunting around, we managed to find some holes in the ceiling, concealed behind rose-shaped bosses, which allowed the warmed air to exit the chamber and enter the roof space,’ says Stevens. In the roof, the ventilation system was originally linked into the flues from the coal-fired boilers using wooden ductwork . The system exploited the pressure differential caused by the upward flow of air from the boiler flues to induce airflow through the council chamber.

The original council chamber ventilation system

SGA Consulting set out to reinstate the original ventilation system, to enhance the airflow without any discernible visual impact in the council chamber. The coal-fired boilers are long gone, but the system still uses the original boiler flue. Because of fire regulations, the Venturi effect from the boiler flue had to be abandoned, so the airflow is now enhanced through the addition of a small axial flow fan.

To further control airflow in the council chamber, motorised dampers (controlled on CO₂ and temperature) have been added to the low-level intakes behind the radiators. Should they so wish, councillors also have the option of opening windows.

SGA Consulting has also managed to hide four cooling-only FCUs beneath raised daises in the council chamber. This helps keep the space comfortable when the council is in session and the room is full of people. The consultant has also resurrected the original Victorian ventilation system in the chamber to further improve comfort.

A major benefit of using a RSHP to provide cooling was that it removed the need for an external air cooled condenser, which would have been noisy and visually obtrusive in this overlooked, congested and historic part of York.

The RSHP is housed on a plinth in the potentially flood-susceptible basement plantroom.

Alongside the electric RSHP, the scheme also includes three new gas-fired boilers. These supply a conventional low-pressure hot water heating circuit at 80^oC flow/70^oC return to furnish the cast iron radiator circuit in the Victorian parts of the building, along with two domestic hot water calorifiers that serve the new kitchen and toilet blocks. The boilers also provide back-up heat to the heat pump circuit, should the heat pump fail.

‘We used the heat pump in all of the spaces where we could make it work, but the heat losses are so great in the Victorian areas, and the floor areas fixed, so we had to reuse existing cast iron radiators and gas boilers to provide sufficient heat,’ explains Stevens.

The new extension to York Guildhall

Heat losses in the 15th-century Guildhall were also particularly high. The building’s Grade I listing meant that it was too difficult to enhance the thermal performance of the solid stone walls and there were insufficient funds to add secondary glazing to the windows. The team was, however, able to hide additional insulation in the roof as part of the lead-replacement works.

Bomb damage during World War II meant that the roof, floor, and some upper walls of the Guildhall had either been rebuilt or replaced, so English Heritage permitted underfloor heating to be installed in the 7m-high space. Even so, heat losses were so great that the heat pump-supplied underfloor heat system alone was insufficient to keep the space comfortable. ‘The heat losses were too high and we were very limited as to the interventions we could make,’ says Stevens.

Boilers are used on very cold days because of high heat losses in the historic buildings

SGA Consulting’s solution was to supplement the underfloor heating with trench heaters concealed within the floor and connected to the higher-temperature gas-fired boiler circuit, for use on cold winter days.

‘When the outside temperature drops below 5^oC, the trench heaters turn on,’ Stevens explains. As a consequence, trench heating will only deliver 12% of the Guildhall’s annual heating demand, with the rest provided by the heat pump circuit. ‘This type of mixed use shows how heat pumps can be used to provide heating to old buildings where the rate of heat loss would be too high otherwise,’ says Stevens.

After the scheme’s completion in 2022, SGA Consulting followed a soft landings regime for two years, to optimise performance of the building services. Lessons learned include:

• Keeping the Guildhall underfloor heating off on cool summer days because of the long time lag in delivering heat
• Turning off the heat to the domestic hot-water systems over weekends when appropriate
• Reminding the client of the two-speed control for kitchen ventilation.

The strategy to re-use a centuries-old building, revitalising it for use for future generations, achieved significant savings on embodied carbon emissions. Equally importantly, the project succeeded in securing the future of the Guildhall complex; the University of York is taking a long-term lease on the historic buildings to create a business hub for spin-off firms from the university. This will contribute to the city’s future and is proof that historic buildings can be refurbished and remodelled to meet contemporary needs.

SGA Consulting’s approach to the project certainly impressed the judges at this year’s CIBSE Building Performance Awards, where the project won a host of awards, including Building Performance Champion.

The judges said of the scheme: ‘With the challenges we face in renovating millions of existing buildings, the York Guildhall project shows what can be achieved to deliver sustainable building refurbishment, minimise embodied carbon and deliver such a project with the most difficult site-access conditions’. 

The post Bridging the gap: the 2024 CIBSE Building Performance Champion appeared first on CIBSE Journal.

The project took place over winter 2022-23, and aimed to gather lessons on retrofit and building performance techniques, which have moved on considerably in 10 years.

Its report looks at how robust, meaningful and useful data are collected in an affordable and accessible manner, and is intended to give occupants, designers and decision-makers a good understanding of BPE.

Analysis of the homes aimed to find out what had stood the test of time, and what lessons there were to learn. The team was particularly interested in moisture, insulation options (moisture and combustibility), and the degradation of original solutions (for example, fabric condition and airtightness).

All 10 sample homes were considered best practice or exemplar at the time, and employed a whole-house ‘deep’ retrofit approach. Six were part of the 2009-13 Retrofit for the Future programme.

Six of the properties dated from pre-1919, nine were houses (one a flat), and they were a mix of housing association and privately owned properties.

Their insulation strategies varied, with a mix of external, internal and cavity insulation, and permeable and impermeable materials. Heating, hot water and ventilation systems were also varied.

A two-tiered BPE approach – core and detailed scope – was followed for the project.

The results:

Energy performance
In most of the homes, no major change has been observed in energy performance compared with the original retrofit energy use. The retrofit has delivered long-term benefits, with energy use still significantly lower than in the average stock.

Tellingly, most homes have reported being satisfied or very satisfied with their energy bills. Where space-heating demand could be estimated, it is in line with best practice retrofit standards, significantly below the national average.

The energy use intensity (EUI) is, on average, ~80kWh·m^-2 GIA per yr, which is very favourable compared with UK data (see table, opposite).

Fabric
Fabric efficiency improvements have been shown to be very effective in the long run, with air leakage and heat demand remaining very low compared with the national average. The good level of performance is indicated by the average for the homes of 2.54m³·h^-1.m^-2 @ 50Pa (up from an average of 1.98 ~10 years ago). Airtightness in all homes is still significantly better than pre-retrofit (77% better as pre-retrofits achieved ~11m³/h.m²@50Pa).

The most common weak point reported by the projects was the lesser reliability of external window and door seals after 10 years of use, in particular on large-format elements, such as doors. Airtightness tapes seem to have held overall, as the drop in performance in some houses is minimal. Only a very few instances have been found of material deterioration, and, in most cases, this has been very localised.

Moisture and mould risks were generally low, with good relative humidity (RH) levels in eight out of nine homes measured, and low or very low Build Test Solutions (BTS) Mould Risk score in seven out of nine homes. The study also recorded generally good CO₂ levels in seven out of nine homes.

A focus on ventilation and maintenance emerged as crucial for long-term success. The findings also reiterated the importance of maintenance. Common issues include clearing gutters and downpipes, and windows and door maintenance.

Systems
The report found that complex systems were more likely to fail. MVHR has been shown to be reliable in these case studies. This was not necessarily expected, as these systems were still quite innovative at the time. Ease of controls remains an issue, even in homes where residents report good comfort and relatively simple systems. There are issues with the metering of solar thermal.

Low carbon strategies since Retrofit for the Future have evolved greatly, in parallel with Grid decarbonisation. Eight out of the 10 homes have a gas boiler, and only one a heat pump. The more common approach now would be for an all-electric system (typically, heat pump) and PVs, rather than solar thermal.

Overall, feedback is very positive, with the sample homes showing results significantly better than the Soap Retrofit benchmark. Comfort has been delivered in all houses and winter comfort is rated very highly in the majority of homes; summer comfort is less so, but no worse than the benchmark. Temperature, RH, and CO₂ are within recommended ranges for most homes.

Evaluation techniques
The common methodology was useful to check and agree an approach and bring consistency, with input from all and an Excel sheet for basic energy reporting. The core and detailed BPE methods proved complementary, and the detailed techniques brought useful additional findings. All homes used the same indoor environmental quality sensors. This helped with consistency of data, allowed the use of the BTS platform for many tests, and supported the evaluators for training and queries.

Challenges
There was a small window to monitor homes over winter, after funding was confirmed in January. More preparation time would have been valuable. Despite initial enquiries with the residents and housing associations about their willingness to engage and the availability of energy data, this proved a challenge in a small number of homes once the study began.

More developed templates would have made reviewing and cross-project data collation and reporting quicker and more consistent, and detailed aspects of the methodology could have been modified or made more explicit. 

A researcher’s perspective

Marion Baeli, was co-leader of the project with CIBSE’s head of net zero policy, Julie Godefroy

Many CIBSE members aren’t engaged in domestic retrofit, says project co-leader Marion Baeli, who was partner at Studio PDP until January and is now principal, sustainability transformation, at 10 Design.

She hopes that the information garnered in the study could be useful for the industry in advising retrofit projects. ‘It’s crucial to conduct the right tests at the starting point, employ appropriate methods, understand the caveats, and ensure a good maintenance plan,’ she says.

Baeli advises that there is no ‘one size fits all’ approach to a retrofit: ‘When you’re starting a project, a retrofit coordinator may be useful in creating a detailed plan, or there are training courses, such as the PAS2035 course, that can be valuable.’

She says that some of her clients are clued up and see the risk of being exposed to high carbon assets. ‘Some clients have approached me to help them address the high carbon intensity of their entire portfolio and identify the best strategy for effective decarbonisation.

‘The aim being to assist them in reducing the risk of their assets becoming stranded. Our guidance focuses on decreasing energy demand initially, followed by transitioning to electricity and renewable energy sources,’ says Baeli.

One major change 10 years on is the profusion of heat pumps. ‘We didn’t know then that there was an alternative to gas boilers’ says Baeli. ‘The main issue at the time was to reduce CO₂. Now the target would be to reduce demand sufficiently to enable you to use an air source heat pump.’

The Retrofit Revisit report emphasises the efficacy of retrofit. ‘We want to give people the confidence that it does work and show that it is a good investment,’ says Baeli. ‘Yes, it’s disruptive, but you only have to do it once for the lifetime of the property and, if you take care of it, it will continue to perform.’ 

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The judges said the entries not only showcase a breadth of innovation, but also reveal a keen understanding of the importance of application flexibility while adhering to stringent regulatory standards. They were impressed by the calibre of the shortlist, saying ‘the range of innovations demonstrates that the product doesn’t have to be epic to be influential and beneficial’.

The CIBSE Building Performance Awards will take place on 29 February 2024 at the Park Plaza Westminster Bridge Hotel in London. To book your place visit bit.ly/CIBSEbpa24.

Stiebel Eltron UK: VLR 70 L Trend

Stiebel Eltron UK introduced its VLR 70 L Trend, a decentralised ventilation unit, in response to the need for landlords and property owners to implement measures to deliver good air quality in social housing and commercial properties. This fully automated unit improves indoor air quality, reduces moisture, and recovers up to 92% of heat, in spaces up to 100m2.

Installed in pairs – either in one or adjoining rooms with good airflow between them – one unit will extract while the other brings in fresh air. The units switch several times a minute between each other to allow the heat exchanger to capture energy from the outbound air, which is then picked up by the incoming air. The unit incorporates smart sensors to account for occupancy, humidity and air quality. With a comprehensive filter system, including F7 filters, the VLR 70 L reduces pollutants, allergens and virus particles.

Vent-Axia: Sentinel Apex

Vent-Axia’s Sentinel Apex commercial heat recovery unit provides fresh, filtered air, combating indoor air pollution and removing pollutants such as moisture and CO2. With up to 93% energy recovery, the unit efficiently uses waste heat, achieving a market-leading 93% thermal efficiency (EN308 tested). Key features include an automatic summer bypass, motor efficiency equivalent to better than IE5 efficiency class, demand control for optimising IAQ, and ultra-low sound levels.

The system was designed for adaptability, energy conservation, and personalised comfort. Vent-Axia’s in-house testing facility and market research informed the unit’s development, focusing on low specific fan power, efficiency, and low sound levels. The unit, which has been specified but not yet installed, is expected to deliver high performance in diverse climates, addressing the demand for sustainable, energy-efficient building solutions.

Glazpart: Link Vent 4000

The Link Vent 4000, a trickle vent for windows and doors to facilitate passive airflow in dwellings, has received excellent feedback for its simple, user-friendly design. An equivalent area of 4,000mm2 is delivered through a 167mm x 13mm slot, reducing routing machine times and waste materials generated. Further increasing its versatility, the Link Vent 4000 can cool a house when overheating or moderate temperatures through smart ventilation when properties become cold and heating is turned on.

The closing action allows more control over draughts by directing air away from occupants, and the split closure plate enables partial opening. The system was created to address the need for ventilation in smaller rooms and aligns with the 2022 legislative changes. Fully compliant with the Building Regulations, the vent enhances air quality and prevents overheating, and received positive feedback from industry leaders.

Daikin: VRV 5 Heat Recovery

Daikin’s VRV 5 Heat Recovery system is a sustainable and efficient HVAC solution for commercial buildings. Its three-pipe heat recovery technology allows simultaneous cooling and heating, enhancing efficiency with a low condensing temperature. The system includes Daikin’s Shîrudo technology, which uses the integration of a sensor, shut-off valves and alarm to detect and isolate potential leaks. Daikin says this enables rooms to be tackled as small as 10m2 without additional calculations or measures.

Daikin also offers embodied energy assessments for the system based on the TM65 calculation methodology. It shows a decrease of up to 53% in embodied carbon. Case studies, such as the University of Lincoln and BBC Earth Experience, showcase successful installations, highlighting the environmental considerations and energy efficiency.

Kampmann UK:WZA – Decentralised Scholl Ventilation Unit

This unit, introduced to the continental European market in late 2021, enhances air quality and minimises virus concentration. It is designed to improve indoor air quality in classrooms, where research has found that elevated CO2 levels can hinder concentration. With a maximum airflow of 280l/s, the WZA unit features automatic airflow control based on CO2 levels, ensuring it stays below a programmed concentration.

Equipped with an enthalpy counterflow plate heat exchanger, the unit efficiently recovers thermal energy and optimises humidity levels, which is particularly beneficial in winter. Operating on mixed-air ventilation principles, it introduces supply air without draughts. The company focuses on minimising whole life carbon, and the WZA materials are designed to be easily taken apart and separated for recycling.

Healthy Air Technology: Distributed Air Purification System

This holistic air purification solution, integrated with BlockDox buildin management systems, takes a novel approach to combine indoor air quality and building performance. By pairing the HA800 air purification technology with BlockDox’s IoT-enabled platform, the solution optimises spaces for health, comfort, and energy efficiency.

The HA800’s multi-layered filtration system captures pollutant particles as small as 0.3 microns, ensuring clean, healthy air. Its closing action controls draughts, and a split closure plate enables partial opening for enhanced user control. By integrating real-time data from the air purifiers and other building systems, BlockDox’s platform empowers precise and responsive management of environments. It is user-friendly and easy to maintain.

The post Air to the throne: Product or Innovation of the Year – Air Quality shortlist appeared first on CIBSE Journal.

The building is made up of three spaces. The main event space is the 21-metre high warehouse, which can be split into two. It is complemented by the hall, a 1,603-seat auditorium with a flexible stage, while a seven-storey tower at the back of the warehouse provides green rooms, dressing rooms and office space.

The building’s façades, of concrete and corrugated metal, contrast with the refurbished brick warehouses and newly built flats, offices, and television studios that make up the new St John’s neighbourhood.

Building services and lighting design had the challenge of responding to the multiple uses of the building while maintaining an industrial aesthetic.

Gas boilers are used for heating currently, but the building is designed to connect into the future St John’s heat network. The hall and warehouse are air cooled and heated, while the tower and social rooms’ loads are met with local emitters. Chillers provide cooling.

Close collaboration between BDP’s electrical, mechanical, lighting and digital engineers was essential because of the complex nature of the internal building geometry, and a BIM model was created to coordinate services.

The BIM model showing the three building elements

The lighting team worked closely with architect OMA and interior designer Brinkworth to coordinate lighting concepts. The result is a combination of general, architectural, experiential, complex emergency, and technical theatrical lighting systems, threaded through the internal building geometry. Three bespoke luminaire types that worked with the contemporary façade design were developed with Stoane Lighting and Zumtobel. In total, 164 luminaire types were used throughout the building.

The energy model demanded >100lm ·W^-1, a significantly higher requirement than that in Part L, which was 60lm ·W^-1 at the time of design in 2018; in the 2021 revision it is 95lm·W^-1. Illumination criteria for general and emergency lighting was determined using the Technical standards for places of entertainment 2015 – The association of British theatre technicians in combination with the usual CIBSE and British Standards. 

The warehouse has capacity for up to 5,000 people standing, and can be divided by a movable, full-height acoustic wall. The hall has a flexible stage that can house an audience of up to 1,600 seated or 2,000 standing. The warehouse and the hall can work together, allowing the stage to extend to a depth of 45 metres. The lighting includes house lighting, management lighting, high output working light, technical space task lighting, and back-of-house blue lighting.

House lighting was provided by ETC ArcSystem luminaire types. These warm white digital multiplex (DMX) fittings mounted to the technical grid allow super low-end DMX dimming to achieve 0.2 lux management light levels. High-output working light illumination of >600 lux was provided by 58,000lm downlights from Glamox. 

In areas where people are working without windows, a 5,000K correlated colour temperature (CCT) has been selected to increase the perception of brightness. Technical spaces use a combination of >500 lux white-light illumination and a blue lighting system for access during a performance. 

Underneath the auditorium

The hall is a traditional raked theatre with removable seating. A range of luminaire types was integrated into the interior architecture to celebrate and delineate the internal geometry, and contribute to house lighting levels. Details include a balcony shadow gap, in-floor uplights, skirt detailing, and uplighting to the soffit from the technical grid edge. A bespoke luminaire was developed to illuminate stair treads. The restricted floor buildup of the auditorium did not allow for a more traditional step-tread lighting solution, so a free-standing, floor-mounted step light was developed that could be installed in the voids below seating.

The warehouse is designed to be a blank canvas. Vertical DMX colour-change linear luminaires around the perimeter can support events with a full-scale lit feature. The general and emergency lighting arrangement allows for cellularisation of the space for set building and isolated space uses.

The tower has multi-level mixed-use spaces connected to the warehouse and includes offices for Manchester International Festival, the green room, and dressing rooms. Most of these spaces have no ceilings and exposed services, so a trunking system was used to minimise ‘visual clutter’. The trunking houses pre-wired power and data, reducing the requirement for secondary containment, making it time- and cost-effective. A range of luminaire types can be inserted, including standalone emergency modules.

Danny Boyle’s version of The Matrix launched the venue last autumn

The main foyer has multiple uses, which is reflected by the lighting. The design responds to the brick arches of the 19th-century railway line that forms part of the foyer. A mixture of adjustable cool-white wide-beam and warm-white narrow-beam track spots are used to create day and evening scenes, combined with uplighting on brick facades.

Integral lighting was used for bar fronts and shelving, and lighting was integrated into the stair handrails, providing localised illumination to the steps, reducing shadowing, and adding a sense of drama. The handrails also provide high-risk emergency lighting. That the building contains very few windows has been used to its advantage by the team, which has harnessed the transformative quality of light to create a variety of scenes and evoke different atmospheres for day and night. 

Outside the building footprint, in the public realm, an undercroft is illuminated with levels suitable for pedestrians and cyclists, ranging from 15 lux to 250 lux, appropriate for daytime and night-time use. 

The design of the services prioritises flexibility, responding to each individual performance and accommodating shows with diverse sets. 

Electrical infrastructure

The electrical infrastructure divides into two systems: house services and a dedicated performance system. This segregation prevents any interference, and handles uneven load distribution. A network of busbars and tap-offs feeds into multi-outlet power panels, complemented by fixed outlets distributed throughout.

A room in the tower

The building boasts an extensive stage lighting and audio visual (SLAV) system, interconnecting outlet panels to form a robust network. A centralised control system oversees this network, employing various AV and data cabling types to match the different shows and setups. 

Strategically placed outlets and power panels in every part of the performance electrical system offer flexibility for main and breakout productions. This, combined with SLAV outlet panels, allows for dynamic show configurations. An advanced performance lighting control system, connected to a central hub, governs performance and house lighting, offering flexible control.

Ventilation and acoustics

A top-down supply ventilation strategy, using swirl jet diffusers, was adopted for the theatre and warehouse to maintain flexibility without introducing physical constraints. To address potential noise challenges, careful diffuser selection was crucial.

Rather than applying a uniform building service noise criterion, specific criteria were established for each event scenario, allowing for more relaxed standards where higher building service noise levels were acceptable. This flexibility matched the requirement for events that needed increased airflow rates, such as high-capacity concerts.

A section view showing the interconnection between the Hall and the Warehouse

Building physics modelling was employed to manage potential noise concerns during heating. This verified that when the hall and warehouse were pre-heated before a show (when higher service noise levels were acceptable) temperatures could be maintained during performances. 

Aviva Studios is an exciting new addition to Manchester’s vibrant cultural scene and the innovative building services engineering and bespoke design allow the operator to create a myriad of performance spaces that put visiting artists in the best possible light. 

• Steve Merridew is a building services engineering director and Nick Meddows is senior lighting designer at BDP

The post Setting the scene: Manchester’s new arts venue Aviva Studios appeared first on CIBSE Journal.

Keeping sellers and collectors comfortable as they negotiate million-dollar art sales is of paramount importance. Frieze Los Angeles is held in a series of temporary tented structures, so controlling the rarefied environment was a particularly demanding challenge for consulting engineer mstep.

‘The galleries can be super-sensitive to environmental conditions,’ says founder of mstep Aleksandra Sasha Krstanovic FCIBSE. ‘Dealers are trading very expensive collections with delicate people. They don’t want to be sitting around getting hot and flustered. We have to be aware of how the temperatures affect the clients and their business.’  

To ensure every gallery at Frieze sits within a comfortable temperature band, Krstanovic has a small army of helpers, with handheld infrared thermometers, recording whether spaces are within an acceptable range. 

mstep has to be aware of rising temperatures when crowds gather

Variations in temperature can be caused by the position of the sun, the proximity of doors and, in some cases, by the biggest celebrities on the planet. ‘Last year, we had Beyoncé visit the show, and it was amazing to see the surge of heat move across the space as the crowds followed behind her,’ remembers Krstanovic. ‘We had to guess where she was going to go next and push the air con up to cool everything down.’

The history of Frieze

Frieze is one of the contemporary art world’s most influential trade fairs, attracting international galleries to exhibit and sell at exhibitions in London, Los Angeles, New York and Seoul. It was set up in London in 2003, before expanding to New York in 2012, Los Angeles in 2019, and Seoul last year.

While the New York and Seoul fairs are held in permanent exhibition centres, the London and LA shows take place in tented structures. In LA, the tents are set up by temporary events specialist Production Glue. It takes four weeks to build the site, in an operation that, according to Krstanovic, ‘requires a remarkable amount of coordination’.

Frieze first came across Krstanovic’s desk while she was working at Aecom as the arts and culture lead, and she took the project with her when she founded mstep, an MEP engineering and environmental consultancy in London. ‘For someone who has an interest in art, Frieze is just phenomenal,’ she says.

Before signing a contract, Krstanovic says a lot of technical design work was undertaken to remove any risk. ‘The main thing was to agree a floating setpoint with Frieze, which we agreed would be 26^oC when the external is not outside of its standard extremes – which, in LA, is 33^oC. If it goes to 40^oC, we are allowed to go higher,’ she says.

The decision to allow for a slight temperature fluctuation makes significant savings in cooling loads. ‘We don’t need to maintain a temperature of 24^oC at all times; if it rises to 26^oC, let it go to 26^oC. The closer we try to control temperatures, the more energy intensive it gets.’

The focus of the Frieze environment is on comfort for visitors, rather than the art. ‘Art doesn’t like big fluctuations or surprises; at a reasonably steady temperature in a tent for five days, it will be fine – art is not as sensitive as many people believe,’ Krstanovic says. 

Temperature control in many temporary events features a conventional overhead fabric duct system with air blown downwards. This is the system used at Frieze London, which took place last month. However, this method is not appropriate in more extreme climates, Krstanovic says, as the 12m height of the tents means a large area has to be heated or cooled before the system affects the 2m high space in which the people are located. In LA, the show takes place in the spring, which means conditions typically vary between 32^oC during the day and 4^oC in the evening. 

To enable air to enter the tent at floor level, mstep made use of the elevated area under the tent structures and designed a system with a network of ducts connected to externally mounted direct expansion air handling units (AHUs) with electric heaters. The air enters the tent through holes cut into the structure’s wooden floor, which are then covered by mesh cages that double as benches.

‘When we saw the opportunity to use the space underneath to move air through ducts, that’s when the idea of the Frieze bench was born,’ says Krstanovic. ‘We presented Frieze with the idea, and they asked how many we needed and said they’d sort it out.’

The benches are spaced at approximately 3m centres and the air enters at up to 800 litres per second at temperatures of between 13^oC and 35^oC. It travels upwards from the grille to the underside of the bench, where it is dispersed sideways through the metal mesh, which acts as support for the bench.

Each AHU is connected, via a duct, to three benches, which enables mstep to vary temperatures and airflows according to the requirements of each gallery. 

‘Temperature can vary across the tent, depending on the flow of the crowd, the position of the sun, and the proximity to the door,’ says Krstanovic. ‘The controllable zones enhance flexibility. While each AHU can only have one environmental regime, having many units means temperatures can be altered between galleries.’

Mstep has learned to protect galleries from cold draughts that are close to air outlets. ‘If there is a gallery in front of the bench, it can be uncomfortable if there is a lot of cool air, and we can include dampers in the supply grilles to moderate flows,’ says Krstanovic.

Since the first LA Frieze, the design of the bench has evolved aesthetically to complement the gallery spaces. Extra mesh in the design makes the seats appear more transparent and congruous, and they are now collapsible, making them easier to store.

In the frame

A grille placed over a vent cut into the wooden floor

Originally at LA Frieze, the holes cut into the wooden floors to enable air to enter the tent were round, but these could not be fitted with standard grilles. This meant people had to stand guard over the openings while precious artwork was manoeuvred into position.

Thanks to a suggestion from Production Glue, square openings are now made, which can be fitted with metal grilles during construction, eliminating the need for human guard rails.

The carpet is laid after the artwork has moved into position, to prevent it from being damaged. The final task before the fair opens is to cut holes in the carpet to expose the grilles and then move the benches on top. ‘It’s a big operation,’ says Krstanovic.

The team at mstep has also come up with a simple, yet incredibly effective, mechanism for regulating the temperature levels within the tent, as Krstanovic explains. ‘We walk around the tent with £30 thermometer guns, taking readings. If temperatures are too high or low, we use WhatsApp groups to talk to the system operatives, who manually tweak the systems’.

The biggest swings in temperature are caused by the crowds – generated by mega celebrities or otherwise. ‘At the start, people arrive at the same time, bringing in body temperature – that’s when we really have to start playing around with the system,’ says Krstanovic, who adds that they look at weather forecasts to predict how temperatures in the tent will change. 

‘It’s incredible what you can do with manual predictive controls. Even in London, with this conventional single overhead duct system, it’s really successful.

The AHUs each serve three benches eg 30C, 30B and 30A

‘We’ve discovered that between 20.5^oC and 21.5^oC is ideal in London. By measuring and communicating the temperature during the day, our teams keep the tent between this 1.5^oC band. You don’t need a super-sophisticated system to do it – just people power. Due to the temporary nature of the fairs, human monitoring and control is most effective,’ she says.  Frieze London also occasionally requires air conditioning – including last month as October was mild.

Teams of six or seven people are on rotation during the day, says Krstanovic. They don’t have to be engineers, but they do need to be conscientious about what they are doing, she says. ‘The tent’s a bit like a sailboat – things go very wrong very quickly. Once temperatures start getting uncomfortable, it’s really hard to bring them back. You can’t let it go – it’s relentless,’ she adds.  

Krstanovic believes continual monitoring and system optimising should be happening in all buildings. ‘Around 90% of all buildings have sufficient hardware to do this. It’s all easy, but we need building management assistance to help FM [facilities management] teams to operate the systems correctly,’ she says.

‘Operational carbon is what we building services engineers deal with – it’s not glamorous, but that’s where the major opportunities are. By monitoring and controlling buildings properly, we can cut energy consumption by 40%.’

This will please green-minded celebrities such as DiCaprio and Jane Fonda, who have visited LA Frieze. The 2023 event was deemed a success, with dealers reporting a ‘fruitful fair with a contagious energy’. A number of works sold for more than $1m, with Mark Bradford’s painting Shall Rest in Honor There topping the sales list at $3.5m. 

In London last month Damien Hirst sold all 12 of his paintings on show and Tracey Emin sold two paintings with a combined value of over £2m. While buyers snapped up the hottest artists, Krstanovic and her team ensured that everyone was able to appreciate the Frieze fair in optimal environmental conditions.

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It is fitting, therefore, that McDonald’s designed and built the world’s first net zero energy fast-food restaurant on the Walt Disney World campus. The all-electric building has achieved more than 105% net positive energy for 12 consecutive months, thanks to a roof-mounted solar photovoltaic array.

Quick-serve restaurants have very high energy use intensity and, with a 24-hour operation, some creative engineering was required to minimise loads.

Cooking appliances consume 55% of the building’s annual energy, while building ventilation is the second-largest load. The majority of ventilation is replacement air for the cooking hood exhaust system, which runs 24 hours per day.

To minimise kitchen exhaust, the kitchen hood exhaust system uses cooking demand-based ventilation controls. These monitor heat, grease and smoke, and adjust exhaust rates to maintain effective capture and containment.

Quick-serve restaurants have large fluctuations in service and have to provide meals to customers on demand. A typical restaurant will keep their cooking lines hot 24 hours a day, so they can react instantly to an influx of customers. This is not only a major energy consumer, but it also adds significant cooling load and keeps the kitchen hood demand-control system from going to minimum flow.

At the Walt Disney World restaurant, McDonald’s deployed a new technology in quick-serve cooking that allows an entire line to go into idle mode and rapidly switch to ‘ready’ when required. This location handles an extraordinarily large number of customers given its proximity to the theme park and has a very large kitchen to handle the demand. There are three cooking lines and being able to bring them to an idle state during lower demand times significantly reduces ventilation and energy load.

Kitchen pressure is held at a 5% negative to adjoining spaces to keep kitchen odours contained. Having a variable exhaust system means the kitchen make-up air unit, and the dedicated outdoor air unit for the adjoining dining room space, must react in sync to maintain a proper pressure balance. Both the make-up air unit and dedicated outdoor air unit have variable speed drives and space-pressure sensors for control. Commissioning this system was complex and required simulation of many scenarios of cooking and occupant loads to tune properly.

The most unique ventilation strategy was the incorporation into the dining room of a natural ventilation system. While this complicates the pressure control of the kitchen, it provides significant energy savings and enhanced occupant comfort.

Orlando is a subtropical climate, classified under the Köppen climatic classification as Cfa. The area has two seasons: hot and rainy, and warm and dry. May to September is considered the hot and rainy season, with high temperatures typically around 32^oC and average lows between 18^oC and 23^oC, with frequent heavy rain. The warm and dry season spans from October through April, with average high temperatures between 20.5^oC and 28.8^oC and lows between 8.8^oC and 18^oC. The warm and dry season experiences about half as much rain as the hot and rainy one.

The operative temperature range for the dining area is between 20^oC and 25.5^oC. Because the restaurant operates 24 hours per day, natural ventilation is available most often at night, when the seasonal temperature ranges are within the operative temperature range. With the wide operative temperature range, the store has 3,800 hours of natural ventilation per year (43%).

The natural ventilation system was commissioned not only to monitor dry bulb temperature, but also enthalpy, wind speed and precipitation. When the weather conditions are within all ranges, operable glass louvres that line the entire south and west façades of the dining area open, while the variable refrigerant flow system providing space conditioning, and the dedicated outdoor air unit providing ventilation, shut down. Natural ventilation fans draw air through the space and help maintain the pressure balance to the kitchen.

Having the natural ventilation glass louvres at the customer level posed a safety concern that had to be accounted for carefully. Louvres could have an item placed in them, or a customer may put their hands in and get them caught.

To address safety concerns, the inside is screened; this also keeps pests or debris from entering the restaurant. On the exterior, a laser system creates a field covering the entire surface of the louvres, and instantly disables actuation of the system if an object is detected. Actuation starts again when the object is removed. An audible message also alerts customers when the louvres open or close, and an internal safety mechanism detects added pressure and prevents complete closure. The commissioning authority tested this and still has all his fingers!

Comfort is maintained in the outdoor area 58% of the time annually between 6am and 6pm

Outdoor dining is not typical with quick-serve restaurants, but this location made that experience the centrepiece of the design. Covered by a sweeping roof made of custom glass panels with amorphous silicon solar photovoltaics, the outdoor dining area is shaded and high-volume, low-speed fans modulate to maintain a comfortable environment.

The shaded environment is comfortable and maintains a similar operative temperature range as the indoor environment, even during some of the hotter temperature conditions. A shading study estimates that comfort is maintained 58% of the time between 6am and 6pm annually. The shaded area also helps precondition the natural ventilation air when that system is active.

The flagship McDonald’s restaurant was originally scheduled to open in April 2020, but this was delayed because of the onset of the Covid-19 pandemic. In July 2020, the restaurant opened for drive-thru service only. The commissioning team took advantage of this opportunity and evaluated and tuned control strategies for the kitchen ventilation systems.

The dining room opened to service in autumn 2020 and the natural ventilation features performed better than anticipated, as temperature and enthalpy ranges were expanded over design setpoint. (See Figure 1). Energy data is tracked live using a monitoring-based commissioning system and is performing better than design. Issues with inverter failures delayed net zero energy performance in the first year of operation. Currently the restaurant is seeking net zero certification through the International Living Futures Institute.

Benjamin Skelton is president at Cyclone Energy Group, which was the commissioning authority and energy expert for the McDonald’s project

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